title: Stimulation of Ca2+-channel Orai1/STIM1 by serum- and glucocorticoid-inducible kinase 1 (SGK1).
abstract: Ca(2+) signaling includes store-operated Ca(2+) entry (SOCE) following depletion of endoplasmic reticulum (ER) Ca(2+) stores. On store depletion, the ER Ca(2+) sensor STIM1 activates Orai1, the pore-forming unit of Ca(2+)-release-activated Ca(2+) (CRAC) channels. Here, we show that Orai1 is regulated by serum- and glucocorticoid-inducible kinase 1 (SGK1), a growth factor-regulated kinase. Membrane Orai1 protein abundance, I(CRAC), and SOCE in human embryonic kidney (HEK293) cells stably expressing Orai1 and transfected with STIM1 were each significantly enhanced by coexpression of constitutively active (S422D)SGK1 (by+81, +378, and+136%, respectively) but not by inactive (K127N)SGK1. Coexpression of the ubiquitin ligase Nedd4-2, an established negatively regulated SGK1 target, down-regulated SOCE (by -48%) and I(CRAC) (by -60%), an effect reversed by expression of (S422D)SGK1 (by +175 and +173%, respectively). Orai1 protein abundance and SOCE were significantly lower in mast cells from SGK1-knockout (sgk1(-/-)) mice (by -37% and -52%, respectively) than in mast cells from wild-type (sgk1(+/+)) littermates. Activation of SOCE by sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase-inhibitor thapsigargin (2 μM) stimulated migration, an effect significantly higher (by +306%) in (S422D)SGK1-expressing than in (K127N)SGK1-expressing HEK293 cells, and also significantly higher (by +108%) in sgk1(+/+) than in sgk1(-/-) mast cells. SGK1 is thus a novel key player in the regulation of SOCE.
authors.affiliation: Department of Physiology, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Eylenstein
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Gehring
authors.forename: Nicole
authors.initials: N
authors.lastname: Heise
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Shumilina
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schmidt
authors.forename: Kalina
authors.initials: K
authors.lastname: Szteyn
authors.forename: Patrick
authors.initials: P
authors.lastname: Münzer
authors.forename: Meerim K
authors.initials: MK
authors.lastname: Nurbaeva
authors.forename: Melanie
authors.initials: M
authors.lastname: Eichenmüller
authors.forename: Leonid
authors.initials: L
authors.lastname: Tyan
authors.forename: Ivonne
authors.initials: I
authors.lastname: Regel
authors.forename: Michael
authors.initials: M
authors.lastname: Föller
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kuhl
authors.forename: Jonathan
authors.initials: J
authors.lastname: Soboloff
authors.forename: Reinhold
authors.initials: R
authors.lastname: Penner
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002460:Cell Line; D002465:Cell Movement; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D000071740:ORAI1 Protein; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D000071737:Stromal Interaction Molecule 1; D000099184:Serum-Glucocorticoid Regulated Kinases
chemical_list: D015220:Calcium Channels; D017874:Immediate-Early Proteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D000071740:ORAI1 Protein; D017346:Protein Serine-Threonine Kinases; D000071737:Stromal Interaction Molecule 1; D000099184:Serum-Glucocorticoid Regulated Kinases; C510746:ORAI1 protein, human; C103530:STIM1 protein, human